If you're well practiced with the sword, you would win against a single hyena. Like Spork said, though, your first strike would have to be a disabling strike. Hyena have outrageous jaw muscles, and if it got hold of you, you'd lose whatever part of you it grabbed.

if you get it with your fit hit, then it's pretty much over, guts spilled, or missing head, you win.

if you miss it with your first hit then you'd wish you had opted for something shorter like a Tanto, co it'sgoing to have your arm off before you can turn that sword round in your other hand to make any useful strokes.

you need to think big, something like a grizzly would be more sporting..